Exterior doors are often used as an architectural feature in a home, business, or other building. In many applications, architects request wood exterior doors to impart a high quality, sophisticated appearance to a structure. Wood doors, for example, can be stained to use the natural wood grain in the exterior design of a structure.
Exterior wood doors typically have left and right wood stiles, top and bottom wood rails extending between the stiles, and a window or panel in the interior region between the stiles and the rails. The wood grain of the stiles typically extends vertically, and the wood grain of the rails typically extends horizontally. The ends of the stiles and rails are accordingly cross-cut transversely with respect to longitudinal vesicles of the wood grain. The open-grain ends of the stiles are thus exposed at the top and bottom of the door, and the open-grain ends of the rails are attached to the inner sides of the stiles. The rails are conventionally attached to the stiles with a plurality of dowels and a single layer of uncured adhesive (e.g., polyvinyl acetate) in the joint between the stiles and the open-grain ends of the rails. The rails and stiles can also have a core of one type of wood, and a veneer of a different type of wood.
Although exterior wood doors are often architecturally desirable, these doors have generally lost market share in recent years to metal and fiberglass doors because exterior wood doors can experience moisture damage if they are not properly treated before installation and not properly maintained afterward. In wet or humid environments, for example, exterior wood doors often absorb moisture in the bottom rail and the lower ends of the stiles absent proper protective coating and sealing. Moisture damage to inadequately sealed/coated exterior wood doors is particularly problematic with structures that do not have a sufficient overhang to protect the doors from rainwater. The moisture cannot readily escape from the rails and stiles, and thus rotting can occur in the lower and upper ends of a door. The moisture in the wood can also warp the rails and the stiles such that the doors may not properly fit in a door frame. Therefore, there is a demand for a moisture-resistant exterior wood door that can withstand wet and/or humid environments for a significant period of time.